1. Technical Field
An aspect of the present invention relates to an image reading apparatus, which is capable of reading images from either side of a sheet.
2. Related Art
An image reading apparatus capable of reading an original image from either side of an original sheet is known. The image reading apparatus may sequentially read images from both sides of the original sheets. When the images on the sheet are read, the sheet may be carried to an image reader unit with a first side (e.g., recto) facing the image reader unit to have the image on the recto read by the image reader unit. Thereafter, the sheet may be reversed to have a second side (e.g., verso) to face the image reader unit. The reversed sheet may be carried to the image reader unit so that the image formed on the verso is read by the same image reader unit. When the images on the two sides are read sequentially, therefore, the sheet with the recto facing the image reader unit and the sheet with the verso facing the image reading unit may be carried to the image reader unit in different sheet conveyer paths.
Due to the difference of the sheet conveyer paths, convey resistance generated with the original sheet and conveyer members (e.g., sheet-conveyer rollers) may vary between the recto-image reading and the verso-image reading, and a first sheet conveying speed to convey the sheet for the recto-image reading and a second sheet conveying speed to convey the sheet for the verso-image reading may vary. When the two sheet conveying speeds are different, magnification ratios of reproduced images to the original images may be different between the reproduced recto and the reproduced verso.
In order to set off the speed difference, for example, an image reading apparatus may be equipped with a mechanism to detect the actual first sheet conveying speed and the second sheet conveying speed and control peripheral speeds of the sheet-conveyer rollers based on the detected actual speeds so that the first and the second sheet conveying speeds become equivalent.